Breakthrough Chip Delivers Better Digital Pictures

I came across this article posted on Technology News Daily and it really intrigued me for a couple of reasons really. First building a better imaging chip that uses less energy is a hot topic right now. Second the guys who developed the chip live and work in Rochester NY. Only the crazy and a handful of smart people actually choose to work and go to school in one of the coldest and darkest areas of North America. I was one of them (you can decide which one I am).

Mark Bocko, professor of electrical and computer engineering, and Zeljko Ignjatovic, assistant professor of electrical and computer engineering at the University of Rochester have devised a prototype digital imaging CMOS chip that both saves energy and improves image quality.

Using over sampling technology at each pixel location these guys developed uses 50 times less energy than the industry’s best imaging chips on market. In addition they open up 1000 times more light recording power. Adding more dynamic range to a digital image would be a huge break through.

Read the technical details below if you dare.

Breakthrough Chip Delivers Better Digital Pictures

A pair of newly patented technologies may soon enable imaging chips to use just a fraction of the energy.

Imaging chips revolutionized the photography industry, and now the chips themselves are being revolutionized. A pair of newly patented technologies may soon enable power-hungry imaging chips to use just a fraction of the energy used today and capture better images while enabling cameras to shrink to the size of a shirt button and run for years on a single battery.

The team from the University of Rochester consisting of Mark Bocko, professor of electrical and computer engineering, and Zeljko Ignjatovic, assistant professor of electrical and computer engineering, has designed a prototype chip that can digitize an image right at each pixel, and they are working now to incorporate a second technology that will compress the image with far fewer computations than the best current compression techniques.

The first technology being developed integrates an oversampling "sigma-delta" analog-to-digital converter at each pixel location in a CMOS sensor. "CMOS" is a common semiconductor fabrication process used in most chips manufactured today. Previous attempts to do this on-pixel conversion have required far too many transistors, leaving too little area to collect light. The new designs use as few as three transistors per pixel, reserving nearly half of the pixel area for light collection. First tests on the chip show that at video rates of 30 frames per second it uses just 0.88 nanowatts per pixel—50 times less than the industry's previous best. It also trounces conventional chips in dynamic range, which is the difference between the dimmest and brightest light it can record. Existing CMOS sensors can record light 1,000 times brighter than their dimmest detectable light, a dynamic range of 1:1,000, while the Rochester technology already demonstrates a dynamic range of 1:100,000.

What makes Bocko and Ignjatovic's method work so elegantly is its feedback design. Traditional CMOS image detectors apply a voltage to charge up a photodiode, and incoming light triggers a release of some of that charge. An amplifying transistor then checks the remaining voltage on the diode, and the diode is recharged again. Bocko and Ignjatovic's design also begins with a charged photodiode that discharges when light reaches it, but the discharge is then measured against a one/zero threshold and the resulting bit is delivered off the chip. If the result of a measurement is a one, then a packet of charge is fed back to the diode, effectively recharging it. The design also uses significantly less power than existing sensor designs, which is especially important in smaller devices like cell phones and digital cameras where battery size is restricted.
The second advance has taken many researchers by surprise.

Called "Focal Plane Image Compression," Bocko and Ignjatovic have figured out a way to arrange photodiodes on an imaging chip so that compressing the resulting image demands as little as 1 percent of the computing power usually needed.

The team members are now looking to build a prototype chip that incorporates both technologies into a single unit to see how much real-world processing power the designs will save. They plan to integrate the technology into wireless security cameras at first.